X-Git-Url: http://git.tuebingen.mpg.de/?a=blobdiff_plain;f=mp4.c;h=7f223bc3ea67853bd2b6e42ee49eeb5f9c3949fe;hb=a8c015f72b358b5f31f35408da8d0983c864aa25;hp=d8aea78379aeabc80987481229c2e537cef8a93f;hpb=06dd900e86fee406c52f18b7dcf81f7487cb7cb6;p=paraslash.git

diff --git a/mp4.c b/mp4.c
index d8aea783..7f223bc3 100644
--- a/mp4.c
+++ b/mp4.c
@@ -62,7 +62,7 @@ struct mp4 {
 	struct mp4_track *track[MAX_TRACKS];
 
 	/* metadata */
-	struct mp4_metadata tags;
+	struct mp4_metadata meta;
 };
 
 int32_t mp4_total_tracks(const struct mp4 *f)
@@ -596,55 +596,24 @@ static int32_t read_stsd(struct mp4 *f)
 	return 0;
 }
 
-static int32_t tag_add_field(struct mp4_metadata *tags, const char *item,
+static int32_t tag_add_field(struct mp4_metadata *meta, const char *item,
 		const char *value, int32_t len)
 {
-	tags->tags = para_realloc(tags->tags,
-		(tags->count + 1) * sizeof(struct mp4_tag));
-	tags->tags[tags->count].item = para_strdup(item);
-	tags->tags[tags->count].len = len;
+	meta->tags = para_realloc(meta->tags,
+		(meta->count + 1) * sizeof(struct mp4_tag));
+	meta->tags[meta->count].item = para_strdup(item);
+	meta->tags[meta->count].len = len;
 	if (len >= 0) {
-		tags->tags[tags->count].value = para_malloc(len + 1);
-		memcpy(tags->tags[tags->count].value, value, len);
-		tags->tags[tags->count].value[len] = 0;
+		meta->tags[meta->count].value = para_malloc(len + 1);
+		memcpy(meta->tags[meta->count].value, value, len);
+		meta->tags[meta->count].value[len] = 0;
 	} else {
-		tags->tags[tags->count].value = para_strdup(value);
+		meta->tags[meta->count].value = para_strdup(value);
 	}
-	tags->count++;
+	meta->count++;
 	return 1;
 }
 
-static const char *ID3v1GenreList[] = {
-	"Blues", "Classic Rock", "Country", "Dance", "Disco", "Funk",
-	"Grunge", "Hip-Hop", "Jazz", "Metal", "New Age", "Oldies",
-	"Other", "Pop", "R&B", "Rap", "Reggae", "Rock",
-	"Techno", "Industrial", "Alternative", "Ska", "Death Metal", "Pranks",
-	"Soundtrack", "Euro-Techno", "Ambient", "Trip-Hop", "Vocal",
-	"Jazz+Funk", "Fusion", "Trance", "Classical", "Instrumental", "Acid",
-	"House", "Game", "Sound Clip", "Gospel", "Noise", "AlternRock", "Bass",
-	"Soul", "Punk", "Space", "Meditative", "Instrumental Pop",
-	"Instrumental Rock", "Ethnic", "Gothic", "Darkwave",
-	"Techno-Industrial", "Electronic", "Pop-Folk", "Eurodance", "Dream",
-	"Southern Rock", "Comedy", "Cult", "Gangsta", "Top 40",
-	"Christian Rap", "Pop/Funk", "Jungle", "Native American", "Cabaret",
-	"New Wave", "Psychadelic", "Rave", "Showtunes", "Trailer", "Lo-Fi",
-	"Tribal", "Acid Punk", "Acid Jazz", "Polka", "Retro", "Musical",
-	"Rock & Roll", "Hard Rock", "Folk", "Folk/Rock", "National Folk",
-	"Swing", "Fast-Fusion", "Bebob", "Latin", "Revival", "Celtic",
-	"Bluegrass", "Avantgarde", "Gothic Rock", "Progressive Rock",
-	"Psychedelic Rock", "Symphonic Rock", "Slow Rock", "Big Band",
-	"Chorus", "Easy Listening", "Acoustic", "Humour", "Speech", "Chanson",
-	"Opera", "Chamber Music", "Sonata", "Symphony", "Booty Bass", "Primus",
-	"Porn Groove", "Satire", "Slow Jam", "Club", "Tango", "Samba",
-	"Folklore", "Ballad", "Power Ballad", "Rhythmic Soul", "Freestyle",
-	"Duet", "Punk Rock", "Drum Solo", "A capella", "Euro-House",
-	"Dance Hall", "Goa", "Drum & Bass", "Club House", "Hardcore", "Terror",
-	"Indie", "BritPop", "NegerPunk", "Polsk Punk", "Beat",
-	"Christian Gangsta", "Heavy Metal", "Black Metal", "Crossover",
-	"Contemporary C", "Christian Rock", "Merengue", "Salsa", "Thrash Metal",
-	"Anime", "JPop", "SynthPop",
-};
-
 static char *read_string(struct mp4 *f, uint32_t length)
 {
 	char *str = para_malloc(length + 1);
@@ -695,7 +664,7 @@ static void parse_tag(struct mp4 *f, uint8_t parent, int32_t size)
 	}
 	if (!data)
 		return;
-	tag_add_field(&f->tags, get_metadata_name(parent), data, len);
+	tag_add_field(&f->meta, get_metadata_name(parent), data, len);
 	free(data);
 }
 
@@ -730,7 +699,7 @@ static int32_t read_mdhd(struct mp4 *f)
 	return 1;
 }
 
-static int32_t parse_metadata(struct mp4 *f, int32_t size)
+static int32_t read_ilst(struct mp4 *f, int32_t size)
 {
 	uint64_t sumsize = 0;
 
@@ -770,11 +739,10 @@ static int32_t read_meta(struct mp4 *f, uint64_t size)
 		subsize = atom_read_header(f, &atom_type, &header_size);
 		if (subsize <= header_size + 4)
 			return 1;
-		if (atom_type == ATOM_ILST) {
-			parse_metadata(f, (uint32_t) (subsize - (header_size + 4)));
-		} else {
+		if (atom_type == ATOM_ILST)
+			read_ilst(f, subsize - (header_size + 4));
+		else
 			set_position(f, get_position(f) + subsize - header_size);
-		}
 		sumsize += subsize;
 	}
 
@@ -892,21 +860,6 @@ struct mp4 *mp4_open_read(const struct mp4_callback *cb)
 	return f;
 }
 
-static int32_t tag_delete(struct mp4_metadata *tags)
-{
-	uint32_t i;
-
-	for (i = 0; i < tags->count; i++) {
-		free(tags->tags[i].item);
-		free(tags->tags[i].value);
-	}
-	free(tags->tags);
-	tags->tags = NULL;
-	tags->count = 0;
-
-	return 0;
-}
-
 void mp4_close(struct mp4 *f)
 {
 	int32_t i;
@@ -923,8 +876,11 @@ void mp4_close(struct mp4 *f)
 			free(f->track[i]);
 		}
 	}
-
-	tag_delete(&(f->tags));
+	for (i = 0; i < f->meta.count; i++) {
+		free(f->meta.tags[i].item);
+		free(f->meta.tags[i].value);
+	}
+	free(f->meta.tags);
 	free(f);
 }
 
@@ -1105,23 +1061,17 @@ struct mp4 *mp4_open_meta(const struct mp4_callback *cb)
 	return f;
 }
 
-int32_t mp4_meta_get_num_items(const struct mp4 *f)
-{
-	return f->tags.count;
-}
-
-int32_t mp4_meta_get_by_index(const struct mp4 *f, uint32_t index,
-				char **item, char **value)
+/**
+ * Return the metadata of an mp4 file.
+ *
+ * \param f As returned by either \ref mp4_open_read() or \ref mp4_open_meta().
+ *
+ * The caller is allowed to add, delete or modify the entries of the returned
+ * structure in order to pass the modified version to \ref mp4_meta_update().
+ */
+struct mp4_metadata *mp4_get_meta(struct mp4 *f)
 {
-	if (index >= f->tags.count) {
-		*item = NULL;
-		*value = NULL;
-		return 0;
-	} else {
-		*item = para_strdup(f->tags.tags[index].item);
-		*value = para_strdup(f->tags.tags[index].value);
-		return 1;
-	}
+	return &f->meta;
 }
 
 static uint32_t find_atom(struct mp4 *f, uint64_t base, uint32_t size,
@@ -1233,14 +1183,6 @@ static unsigned membuffer_write_atom_name(struct membuffer *buf, const char *dat
 	return membuffer_write(buf, data, 4) == 4 ? 1 : 0;
 }
 
-static unsigned membuffer_write_int16(struct membuffer *buf, uint16_t data)
-{
-	uint8_t temp[2];
-
-	write_u16_be(temp, data);
-	return membuffer_write(buf, temp, 2);
-}
-
 static unsigned membuffer_write_int32(struct membuffer *buf, uint32_t data)
 {
 	uint8_t temp[4];
@@ -1248,131 +1190,22 @@ static unsigned membuffer_write_int32(struct membuffer *buf, uint32_t data)
 	return membuffer_write(buf, temp, 4);
 }
 
-static void membuffer_write_track_tag(struct membuffer *buf, const char *name,
-		uint32_t index, uint32_t total)
-{
-	membuffer_write_int32(buf,
-		8 /*atom header */  + 8 /*data atom header */  +
-		8 /*flags + reserved */  + 8 /*actual data */ );
-	membuffer_write_atom_name(buf, name);
-	membuffer_write_int32(buf,
-		8 /*data atom header */  +
-		8 /*flags + reserved */  + 8 /*actual data */ );
-	membuffer_write_atom_name(buf, "data");
-	membuffer_write_int32(buf, 0);	//flags
-	membuffer_write_int32(buf, 0);	//reserved
-	membuffer_write_int16(buf, 0);
-	membuffer_write_int16(buf, (uint16_t) index);	//track number
-	membuffer_write_int16(buf, (uint16_t) total);	//total tracks
-	membuffer_write_int16(buf, 0);
-}
-
-static void membuffer_write_int16_tag(struct membuffer *buf, const char *name,
-		uint16_t value)
-{
-	membuffer_write_int32(buf,
-		8 /*atom header */  + 8 /*data atom header */  +
-		8 /*flags + reserved */  + 2 /*actual data */ );
-	membuffer_write_atom_name(buf, name);
-	membuffer_write_int32(buf,
-		8 /*data atom header */  +
-		8 /*flags + reserved */  + 2 /*actual data */ );
-	membuffer_write_atom_name(buf, "data");
-	membuffer_write_int32(buf, 0);	//flags
-	membuffer_write_int32(buf, 0);	//reserved
-	membuffer_write_int16(buf, value);	//value
-}
-
-static uint32_t myatoi(const char *param)
-{
-	return param ? atoi(param) : 0;
-}
-
-static uint32_t meta_genre_to_index(const char *genrestr)
-{
-	unsigned n;
-	for (n = 0; n < sizeof (ID3v1GenreList) / sizeof (ID3v1GenreList[0]); n++) {
-		if (!strcasecmp(genrestr, ID3v1GenreList[n]))
-			return n + 1;
-	}
-	return 0;
-}
-
-struct stdmeta_entry {
-	const char *atom;
-	const char *name;
-};
-
-struct stdmeta_entry stdmetas[] = {
-	{"\xA9" "nam", "title"},
-	{"\xA9" "ART", "artist"},
-	{"\xA9" "wrt", "writer"},
-	{"\xA9" "alb", "album"},
-	{"\xA9" "day", "date"},
-	{"\xA9" "too", "tool"},
-	{"\xA9" "cmt", "comment"},
-	{"cpil", "compilation"},
-	{"covr", "cover"},
-	{"aART", "album_artist"},
-};
-
-static const char *find_standard_meta(const char *name)	//returns atom name if found, 0 if not
-{
-	unsigned n;
-	for (n = 0; n < sizeof (stdmetas) / sizeof (stdmetas[0]); n++) {
-		if (!strcasecmp(name, stdmetas[n].name))
-			return stdmetas[n].atom;
-	}
-	return 0;
-}
-
 static void membuffer_write_std_tag(struct membuffer *buf, const char *name,
 		const char *value)
 {
-	uint32_t flags = 1;
-
-	/* special check for compilation flag */
-	if (strcmp(name, "cpil") == 0) {
-		flags = 21;
-	}
-
-	membuffer_write_int32(buf,
-		8 /*atom header */  + 8 /*data atom header */  +
-		8 /*flags + reserved */  + strlen(value));
+	uint32_t len = strlen(value);
+	membuffer_write_int32(buf, 8 /* atom header */
+		+ 8 /* data atom header */
+		+ 8 /* flags + reserved */
+		+ len);
 	membuffer_write_atom_name(buf, name);
-	membuffer_write_int32(buf,
-		8 /*data atom header */  +
-		8 /*flags + reserved */  + strlen(value));
+	membuffer_write_int32(buf, 8 /* data atom header */
+		+ 8 /* flags + reserved */
+		+ len);
 	membuffer_write_atom_name(buf, "data");
-	membuffer_write_int32(buf, flags);	//flags
-	membuffer_write_int32(buf, 0);	//reserved
-	membuffer_write(buf, value, strlen(value));
-}
-
-static void membuffer_write_custom_tag(struct membuffer *buf, const char *name,
-		const char *value)
-{
-	membuffer_write_int32(buf,
-		8 /*atom header */  +
-		0x1C /*weirdo itunes atom */  +
-		12 /*name atom header */  + strlen(name) +
-		16 /*data atom header + flags */  + strlen(value));
-	membuffer_write_atom_name(buf, "----");
-	membuffer_write_int32(buf, 0x1C);	//weirdo itunes atom
-	membuffer_write_atom_name(buf, "mean");
-	membuffer_write_int32(buf, 0);
-	membuffer_write(buf, "com.apple.iTunes", 16);
-	membuffer_write_int32(buf, 12 + strlen(name));
-	membuffer_write_atom_name(buf, "name");
-	membuffer_write_int32(buf, 0);
-	membuffer_write(buf, name, strlen(name));
-	membuffer_write_int32(buf,
-		8 /*data atom header */  +
-		8 /*flags + reserved */  + strlen(value));
-	membuffer_write_atom_name(buf, "data");
-	membuffer_write_int32(buf, 1);	//flags
-	membuffer_write_int32(buf, 0);	//reserved
-	membuffer_write(buf, value, strlen(value));
+	membuffer_write_int32(buf, 1);	/* flags */
+	membuffer_write_int32(buf, 0);	/* reserved */
+	membuffer_write(buf, value, len);
 }
 
 static unsigned membuffer_error(const struct membuffer *buf)
@@ -1403,78 +1236,41 @@ static void *membuffer_detach(struct membuffer *buf)
 	return ret;
 }
 
-static uint32_t create_ilst(const struct mp4_metadata *data, void **out_buffer,
+struct stdmeta_entry {
+	const char *atom;
+	const char *name;
+};
+
+static const char *find_standard_meta(const char *name)
+{
+	const struct stdmeta_entry stdmetas[] = {
+		{"\xA9" "nam", "title"},
+		{"\xA9" "ART", "artist"},
+		{"\xA9" "alb", "album"},
+		{"\xA9" "day", "date"},
+		{"\xA9" "cmt", "comment"},
+	};
+
+	for (unsigned n = 0; n < ARRAY_SIZE(stdmetas); n++)
+		if (!strcasecmp(name, stdmetas[n].name))
+			return stdmetas[n].atom;
+	return NULL;
+}
+
+static uint32_t create_ilst(const struct mp4_metadata *meta, void **out_buffer,
 		uint32_t * out_size)
 {
 	struct membuffer *buf = membuffer_create();
 	unsigned metaptr;
-	char *mask = para_calloc(data->count);
-	const char *tracknumber_ptr = 0, *totaltracks_ptr = 0;
-	const char *discnumber_ptr = 0, *totaldiscs_ptr = 0;
-	const char *genre_ptr = 0, *tempo_ptr = 0;
-
-	for (metaptr = 0; metaptr < data->count; metaptr++) {
-		struct mp4_tag *tag = &data->tags[metaptr];
-		if (!strcasecmp(tag->item, "tracknumber")
-				|| !strcasecmp(tag->item, "track")) {
-			if (tracknumber_ptr == 0)
-				tracknumber_ptr = tag->value;
-			mask[metaptr] = 1;
-		} else if (!strcasecmp(tag->item, "totaltracks")) {
-			if (totaltracks_ptr == 0)
-				totaltracks_ptr = tag->value;
-			mask[metaptr] = 1;
-		} else if (!strcasecmp(tag->item, "discnumber")
-				|| !strcasecmp(tag->item, "disc")) {
-			if (discnumber_ptr == 0)
-				discnumber_ptr = tag->value;
-			mask[metaptr] = 1;
-		} else if (!strcasecmp(tag->item, "totaldiscs")) {
-			if (totaldiscs_ptr == 0)
-				totaldiscs_ptr = tag->value;
-			mask[metaptr] = 1;
-		} else if (!strcasecmp(tag->item, "genre")) {
-			if (genre_ptr == 0)
-				genre_ptr = tag->value;
-			mask[metaptr] = 1;
-		} else if (!strcasecmp(tag->item, "tempo")) {
-			if (tempo_ptr == 0)
-				tempo_ptr = tag->value;
-			mask[metaptr] = 1;
-		}
-	}
 
-	if (tracknumber_ptr)
-		membuffer_write_track_tag(buf, "trkn", myatoi(tracknumber_ptr),
-			 myatoi(totaltracks_ptr));
-	if (discnumber_ptr)
-		membuffer_write_track_tag(buf, "disk", myatoi(discnumber_ptr),
-			 myatoi(totaldiscs_ptr));
-	if (tempo_ptr)
-		membuffer_write_int16_tag(buf, "tmpo", myatoi(tempo_ptr));
-
-	if (genre_ptr) {
-		uint32_t index = meta_genre_to_index(genre_ptr);
-		if (index == 0)
-			membuffer_write_std_tag(buf, "©gen", genre_ptr);
-		else
-			membuffer_write_int16_tag(buf, "gnre", index);
-	}
-	for (metaptr = 0; metaptr < data->count; metaptr++) {
-		struct mp4_tag *tag;
-		const char *std_meta_atom;
-
-		if (mask[metaptr])
-			continue;
-		tag = &data->tags[metaptr];
-		std_meta_atom = find_standard_meta(tag->item);
+	for (metaptr = 0; metaptr < meta->count; metaptr++) {
+		struct mp4_tag *tag = meta->tags + metaptr;
+		const char *std_meta_atom = find_standard_meta(tag->item);
 		if (std_meta_atom)
 			membuffer_write_std_tag(buf, std_meta_atom, tag->value);
 		else
-			membuffer_write_custom_tag(buf, tag->item, tag->value);
+			PARA_ERROR_LOG("invalid tag item: %s\n", tag->item);
 	}
-	free(mask);
-
 	if (membuffer_error(buf)) {
 		membuffer_free(buf);
 		return 0;
@@ -1528,14 +1324,14 @@ static unsigned membuffer_transfer_from_file(struct membuffer *buf, struct mp4 *
 	return bytes;
 }
 
-static uint32_t create_meta(const struct mp4_metadata *data, void **out_buffer,
+static uint32_t create_meta(const struct mp4_metadata *meta, void **out_buffer,
 		uint32_t * out_size)
 {
 	struct membuffer *buf;
 	uint32_t ilst_size;
 	void *ilst_buffer;
 
-	if (!create_ilst(data, &ilst_buffer, &ilst_size))
+	if (!create_ilst(meta, &ilst_buffer, &ilst_size))
 		return 0;
 
 	buf = membuffer_create();
@@ -1550,14 +1346,14 @@ static uint32_t create_meta(const struct mp4_metadata *data, void **out_buffer,
 	return 1;
 }
 
-static uint32_t create_udta(const struct mp4_metadata *data, void **out_buffer,
+static uint32_t create_udta(const struct mp4_metadata *meta, void **out_buffer,
 uint32_t * out_size)
 {
 	struct membuffer *buf;
 	uint32_t meta_size;
 	void *meta_buffer;
 
-	if (!create_meta(data, &meta_buffer, &meta_size))
+	if (!create_meta(meta, &meta_buffer, &meta_size))
 		return 0;
 
 	buf = membuffer_create();
@@ -1577,8 +1373,7 @@ static uint32_t fix_byte_order_32(uint32_t src)
 	return read_u32_be(&src);
 }
 
-static uint32_t modify_moov(struct mp4 *f, const struct mp4_metadata *data,
-		void **out_buffer, uint32_t * out_size)
+static void *modify_moov(struct mp4 *f, uint32_t *out_size)
 {
 	uint64_t total_base = f->moov_offset + 8;
 	uint32_t total_size = (uint32_t) (f->moov_size - 8);
@@ -1587,7 +1382,7 @@ static uint32_t modify_moov(struct mp4 *f, const struct mp4_metadata *data,
 	uint32_t udta_size, meta_size, ilst_size;
 
 	uint32_t new_ilst_size;
-	void *new_ilst_buffer;
+	void *new_ilst_buffer, *out_buffer;
 
 	uint8_t *p_out;
 	int32_t size_delta;
@@ -1596,8 +1391,8 @@ static uint32_t modify_moov(struct mp4 *f, const struct mp4_metadata *data,
 		struct membuffer *buf;
 		void *new_udta_buffer;
 		uint32_t new_udta_size;
-		if (!create_udta(data, &new_udta_buffer, &new_udta_size))
-			return 0;
+		if (!create_udta(&f->meta, &new_udta_buffer, &new_udta_size))
+			return NULL;
 
 		buf = membuffer_create();
 		set_position(f, total_base);
@@ -1609,86 +1404,77 @@ static uint32_t modify_moov(struct mp4 *f, const struct mp4_metadata *data,
 		free(new_udta_buffer);
 
 		*out_size = membuffer_get_size(buf);
-		*out_buffer = membuffer_detach(buf);
+		out_buffer = membuffer_detach(buf);
 		membuffer_free(buf);
-		return 1;
-	} else {
-		udta_offset = get_position(f);
-		udta_size = read_int32(f);
-		if (!find_atom_v2 (f, udta_offset + 8, udta_size - 8, "meta", 4, "ilst")) {
-			struct membuffer *buf;
-			void *new_meta_buffer;
-			uint32_t new_meta_size;
-			if (!create_meta(data, &new_meta_buffer, &new_meta_size))
-				return 0;
-
-			buf = membuffer_create();
-			set_position(f, total_base);
-			membuffer_transfer_from_file(buf, f,
-				(uint32_t)(udta_offset - total_base));
-
-			membuffer_write_int32(buf, udta_size + 8 + new_meta_size);
-			membuffer_write_atom_name(buf, "udta");
-			membuffer_transfer_from_file(buf, f, udta_size);
-
-			membuffer_write_atom(buf, "meta", new_meta_size,
-				new_meta_buffer);
-			free(new_meta_buffer);
-
-			*out_size = membuffer_get_size(buf);
-			*out_buffer = membuffer_detach(buf);
-			membuffer_free(buf);
-			return 1;
-		}
-		meta_offset = get_position(f);
-		meta_size = read_int32(f);
-		if (!find_atom(f, meta_offset + 12, meta_size - 12, "ilst"))
-			return 0;	//shouldn't happen, find_atom_v2 above takes care of it
-		ilst_offset = get_position(f);
-		ilst_size = read_int32(f);
+		return out_buffer;
+	}
+	udta_offset = get_position(f);
+	udta_size = read_int32(f);
+	if (!find_atom_v2 (f, udta_offset + 8, udta_size - 8, "meta", 4, "ilst")) {
+		struct membuffer *buf;
+		void *new_meta_buffer;
+		uint32_t new_meta_size;
+
+		if (!create_meta(&f->meta, &new_meta_buffer, &new_meta_size))
+			return NULL;
 
-		if (!create_ilst(data, &new_ilst_buffer, &new_ilst_size))
-			return 0;
+		buf = membuffer_create();
+		set_position(f, total_base);
+		membuffer_transfer_from_file(buf, f,
+			(uint32_t)(udta_offset - total_base));
 
-		size_delta = new_ilst_size - (ilst_size - 8);
+		membuffer_write_int32(buf, udta_size + 8 + new_meta_size);
+		membuffer_write_atom_name(buf, "udta");
+		membuffer_transfer_from_file(buf, f, udta_size);
 
-		*out_size = total_size + size_delta;
-		*out_buffer = para_malloc(*out_size);
-		p_out = (uint8_t *) * out_buffer;
+		membuffer_write_atom(buf, "meta", new_meta_size,
+			new_meta_buffer);
+		free(new_meta_buffer);
 
-		set_position(f, total_base);
-		read_data(f, p_out,
-				(uint32_t) (udta_offset - total_base));
-		p_out += (uint32_t) (udta_offset - total_base);
-		*(uint32_t *) p_out = fix_byte_order_32(read_int32(f) + size_delta);
-		p_out += 4;
-		read_data(f, p_out, 4);
-		p_out += 4;
-		read_data(f, p_out,
-				(uint32_t) (meta_offset - udta_offset - 8));
-		p_out += (uint32_t) (meta_offset - udta_offset - 8);
-		*(uint32_t *) p_out = fix_byte_order_32(read_int32(f) + size_delta);
-		p_out += 4;
-		read_data(f, p_out, 4);
-		p_out += 4;
-		read_data(f, p_out,
-				(uint32_t) (ilst_offset - meta_offset - 8));
-		p_out += (uint32_t) (ilst_offset - meta_offset - 8);
-		*(uint32_t *) p_out = fix_byte_order_32(read_int32(f) + size_delta);
-		p_out += 4;
-		read_data(f, p_out, 4);
-		p_out += 4;
-
-		memcpy(p_out, new_ilst_buffer, new_ilst_size);
-		p_out += new_ilst_size;
-
-		set_position(f, ilst_offset + ilst_size);
-		read_data(f, p_out, (uint32_t) (total_size
-			- (ilst_offset - total_base) - ilst_size));
-
-		free(new_ilst_buffer);
+		*out_size = membuffer_get_size(buf);
+		out_buffer = membuffer_detach(buf);
+		membuffer_free(buf);
+		return out_buffer;
 	}
-	return 1;
+	meta_offset = get_position(f);
+	meta_size = read_int32(f);
+ 	/* shouldn't happen, find_atom_v2 above takes care of it */
+	if (!find_atom(f, meta_offset + 12, meta_size - 12, "ilst"))
+		return NULL;
+	ilst_offset = get_position(f);
+	ilst_size = read_int32(f);
+	if (!create_ilst(&f->meta, &new_ilst_buffer, &new_ilst_size))
+		return NULL;
+	size_delta = new_ilst_size - (ilst_size - 8);
+	*out_size = total_size + size_delta;
+	out_buffer = para_malloc(*out_size);
+	p_out = out_buffer;
+	set_position(f, total_base);
+	read_data(f, p_out, (uint32_t) (udta_offset - total_base));
+	p_out += (uint32_t) (udta_offset - total_base);
+	*(uint32_t *)p_out = fix_byte_order_32(read_int32(f) + size_delta);
+	p_out += 4;
+	read_data(f, p_out, 4);
+	p_out += 4;
+	read_data(f, p_out, (uint32_t) (meta_offset - udta_offset - 8));
+	p_out += (uint32_t) (meta_offset - udta_offset - 8);
+	*(uint32_t *)p_out = fix_byte_order_32(read_int32(f) + size_delta);
+	p_out += 4;
+	read_data(f, p_out, 4);
+	p_out += 4;
+	read_data(f, p_out, (uint32_t) (ilst_offset - meta_offset - 8));
+	p_out += (uint32_t) (ilst_offset - meta_offset - 8);
+	*(uint32_t *)p_out = fix_byte_order_32(read_int32(f) + size_delta);
+	p_out += 4;
+	read_data(f, p_out, 4);
+	p_out += 4;
+	memcpy(p_out, new_ilst_buffer, new_ilst_size);
+	p_out += new_ilst_size;
+	set_position(f, ilst_offset + ilst_size);
+	read_data(f, p_out, (uint32_t) (total_size
+		- (ilst_offset - total_base) - ilst_size));
+	free(new_ilst_buffer);
+	return out_buffer;
 }
 
 static int32_t write_data(struct mp4 *f, void *data, uint32_t size)
@@ -1709,21 +1495,17 @@ static int32_t write_int32(struct mp4 *f, uint32_t data)
 	return write_data(f, temp, sizeof(temp));
 }
 
-int32_t mp4_meta_update(const struct mp4_callback *cb,
-		const struct mp4_metadata *data)
+int32_t mp4_meta_update(struct mp4 *f)
 {
 	void *new_moov_data;
 	uint32_t new_moov_size;
 
-	struct mp4 *f = para_calloc(sizeof(struct mp4));
-	f->cb = cb;
 	set_position(f, 0);
-	parse_atoms(f, 1);
-	if (!modify_moov(f, data, &new_moov_data, &new_moov_size)) {
+	new_moov_data = modify_moov(f, &new_moov_size);
+	if (!new_moov_data ) {
 		mp4_close(f);
 		return 0;
 	}
-
 	/* copy moov atom to end of the file */
 	if (f->last_atom != ATOM_MOOV) {
 		char *free_data = "free";
@@ -1742,52 +1524,75 @@ int32_t mp4_meta_update(const struct mp4_callback *cb,
 		write_data(f, "moov", 4);
 		write_data(f, new_moov_data, new_moov_size);
 	}
-	cb->truncate(cb->user_data);
-	mp4_close(f);
+	free(new_moov_data);
+	f->cb->truncate(f->cb->user_data);
 	return 1;
 }
 
-/* find a metadata item by name */
-/* returns 0 if item found, 1 if no such item */
-static int32_t meta_find_by_name(const struct mp4 *f, const char *item,
-		char **value)
+static char *meta_find_by_name(const struct mp4 *f, const char *item)
 {
 	uint32_t i;
 
-	for (i = 0; i < f->tags.count; i++) {
-		if (!strcasecmp(f->tags.tags[i].item, item)) {
-			*value = para_strdup(f->tags.tags[i].value);
-			return 1;
-		}
-	}
-
-	*value = NULL;
-
-	/* not found */
-	return 0;
+	for (i = 0; i < f->meta.count; i++)
+		if (!strcasecmp(f->meta.tags[i].item, item))
+			return para_strdup(f->meta.tags[i].value);
+	return NULL;
 }
 
-int32_t mp4_meta_get_artist(const struct mp4 *f, char **value)
+/**
+ * Return the value of the artist meta tag of an mp4 file.
+ *
+ * \param f Must not be NULL.
+ *
+ * \return If the file does not contain this metadata tag, the function returns
+ * NULL. Otherwise, a copy of the tag value is returned. The caller should free
+ * this memory when it is no longer needed.
+ */
+char *mp4_meta_get_artist(const struct mp4 *f)
 {
-	return meta_find_by_name(f, "artist", value);
+	return meta_find_by_name(f, "artist");
 }
 
-int32_t mp4_meta_get_title(const struct mp4 *f, char **value)
+/**
+ * Return the value of the title meta tag of an mp4 file.
+ *
+ * \param f See \ref mp4_meta_get_artist().
+ * \return See \ref mp4_meta_get_artist().
+ */
+char *mp4_meta_get_title(const struct mp4 *f)
 {
-	return meta_find_by_name(f, "title", value);
+	return meta_find_by_name(f, "title");
 }
 
-int32_t mp4_meta_get_date(const struct mp4 *f, char **value)
+/**
+ * Return the value of the date meta tag of an mp4 file.
+ *
+ * \param f See \ref mp4_meta_get_artist().
+ * \return See \ref mp4_meta_get_artist().
+ */
+char *mp4_meta_get_date(const struct mp4 *f)
 {
-	return meta_find_by_name(f, "date", value);
+	return meta_find_by_name(f, "date");
 }
 
-int32_t mp4_meta_get_album(const struct mp4 *f, char **value)
+/**
+ * Return the value of the album meta tag of an mp4 file.
+ *
+ * \param f See \ref mp4_meta_get_artist().
+ * \return See \ref mp4_meta_get_artist().
+ */
+char *mp4_meta_get_album(const struct mp4 *f)
 {
-	return meta_find_by_name(f, "album", value);
+	return meta_find_by_name(f, "album");
 }
 
-int32_t mp4_meta_get_comment(const struct mp4 *f, char **value)
+/**
+ * Return the value of the comment meta tag of an mp4 file.
+ *
+ * \param f See \ref mp4_meta_get_artist().
+ * \return See \ref mp4_meta_get_artist().
+ */
+char *mp4_meta_get_comment(const struct mp4 *f)
 {
-	return meta_find_by_name(f, "comment", value);
+	return meta_find_by_name(f, "comment");
 }